1. Field of the Invention
The present invention relates to an image heating device configured to heat an image on a recording material. As examples of such image heating device, there are fixing devices used in copying machines, printers, and facsimile machines employing electrophotographic recording methods or electrostatic recording methods, as well as glossiness increasing devices for increasing glossiness of the image.
2. Description of the Related Art
In conventional fixing devices used in electrophotographic image forming devices, a heat roller fixing method which uses a pair of rollers for heating and pressing is often employed. In recent years, in order to accommodate higher-speed image forming, a belt fixing device employing a belt for heating or pressing has been proposed. For example, in the belt fixing device discussed in Japanese Patent Application Laid-open No. 9-034291, pressure is applied from the inner surface of a belt by using a pressure pad in order to increase the width of a fixing nip. Japanese Patent Application Laid-open No. 11-045018 discusses a belt fixing device in which oil is applied onto the inner surface of a belt in order to decrease sliding friction between the pressure pad and the inner surface of the belt.
Further, Japanese Patent Application Laid-open No. 11-024458 discusses a belt fixing device in which rocking control is performed in a direction of the belt's width by repeatedly displacing a steering roller which suspends the belt.
However, in the above-mentioned conventional art, there are problems described below.
That is, if oil supply is increased for a lengthened time in order to decrease sliding friction between the pressure pad and the belt, a large amount of oil may adhere to the steering roller, and it may be difficult for the belt to follow the displacement of the steering roller. As a result, the control of rocking of the belt may not be appropriately performed.